View Full Version : Bootable backup over the network?

06-24-2009, 07:18 PM

(I've just had to do a full system restore from a bootable backup, and it worked perfectly! thanks for this great software!)

I have seen in the user's guide that one can make a bootable backup only on a wired (USB/Firewire) drive, not on a network drive. This seems to be because backing up on a network drive results in a sparse image, which is not bootable.

I would like to understand why this is so, in particular, why is it not possible to make a bootable backup to a network drive.
Is this an inherent technical limitation of how remote copying works?

or maybe I'm just plain wrong in my understanding of the user guide, and one can in fact have SD do a bootable backup over the air?


-- Éric

06-24-2009, 07:24 PM
It's a technical limitation. When you're working with a network volume, you're working with a totally different file system - basically, a virtualized copy. You can't fully preserve all the information you need to preserve, and can't authorize sufficiently -- without an agent running on the far side -- to even write "system" owned files.

This is why both SuperDuper! and Time Machine use images as 'containers' - those images act like local drives, so we can preserve what we need to. But they can't be booted from - because they're not real drives.

06-24-2009, 07:41 PM
Thanks, that clarifies the matter. Although it would be really cool to have a workaround to this, so as to be able to have a bootable backup without having to plug anything...

-- Éric

06-24-2009, 07:43 PM
Not likely to happen, Éric -- at least not without extensive OS X support for that kind of thing. (NetBoot, which works with OS X server, is something else entirely.)

07-14-2009, 05:56 PM
I just downloaded SD today for evaluation, and was hoping to be able to create a bootable copy via the network (planning to get an AE base station soon).

I planned to create the inital backup to a locally attached USB drive, then hook that drive to the network for incremental updates.
After coming across this post, I sadly realize this probably won't work, even with HFS+/Journaled formatted drives and over AFP (right?).

May I suggest a feature then (couldn't find anything like that in the docs or in the forum): How about the ability to create a bootable mini system on the same drive that's able to (1) boot the Mac when plugged in directly, (2) mount the image and (3) restore all the files?

I realize this could probably be done via booting from the original CD/DVD, but I find that procedure highly annoying (esp. searching for those CDs/DVDs).

07-14-2009, 06:48 PM
Well, you can partition the drive and install a basic installation of OSX on that drive, or do so to a memory stick...

Also, see the "Airport Disks" post at the Shirt Pocket blog for a discussion of the best way to do the local backup...

07-16-2009, 12:11 PM

thank you for your reply.
However, some bits of the "Airport Disks" article leave me a bit confused, even after looking into the SD manual.

Especially this:
"I'd suggest doing your first full backup directly to the USB drive, rather than over the network. This'll be a lot faster. You can then connect the drive to the base station, and re-select the image using the "Disk Image..." choice in SuperDuper!'s destination drive pop-up."

How is creating a sparse image wih SD different from using Disk Utility? Do I have to determine a maximum size in advance? (IIRC, I have to do so with Disk Utility.)
Can I create an AES-encrypted sparse image with Disk Utility and use that for backup with SD? I found this thread which seems to indicate yes, just would like to get a confirmation:

As for the minimum system for booting up, mounting the image and restoring, it would *really* have to be sized down to the bare essentials. My backup drive's size closely matches my MB's drive size, so the backup image should match this size as closely as possible as well, not leaving much room for an additional OS.
Unfortunately, I can't find the 10.5 installer dvd for my laptop, so I would have to transfer the necessary files manually.
Any pointers to a tutorial how to do that?

07-16-2009, 12:18 PM
Creating it with SD! or with DU is the same: we both use the same thing, and both have maximum sizes. If you want it encrypted, you'd need to create yourself, but you can still use the general steps provided.

Can't really help you with a stripped-down base system... that's why a basic install is helpful. Hard without the DVD, of course. I'd actually do it with a thumb drive if you have an Intel Mac.

07-24-2009, 08:28 AM
Ok I fixed my original post. Can you just confirm that I cannot back up all my files from the network, without reinstalling OSX?

07-24-2009, 09:23 AM
I'm not sure what "original post" you mean here. There's nothing else in this thread from you.

You don't need to reinstall OSX to "Back up files", although you can't back up files "from the network"... perhaps I don't understand what you mean.